Sealing device



Sept. 23, 1952 Wlllllllll ill B. GROSS SEALING DEVICE Filed NOV. 25, 1949 INVENToR.

Patented Sept. 23, 1952 VBernard Gross, .SanDiego, :.Calit, ,.a-ssignor, by

lmesme assignments, .to RolirAircraft Gomeravtion,..a corporationof California y s f ApplieationNovember25, 1949Seral-Nc."129;253`A' K 2..C1ims. (C1. 78-e5. 1) y :My :invention relates `to 'sealing fdeviees femployedzfor:sealingrivetsgboltsfscrews.or thezlike, particularly thoseof thecountersunkftype.

The principalobjectof-the invention ,is .to provide :means ,for hermetically .sealing -a conventional insert "type fastener, such as arivet or vfbolt.A where Ysuch fasteners :arerequired `to have .resistance :to leakage, Vasin the fabrication of .pressure vessels, integral'fuel tanks* inA the YWings of'airCraft, .gas chambers, pressure accumulavters, :pressurized ,airplane cabins or compartments, fluid-tight .bulkheads inV air :or watercraft,

water-tighthulls of seaplanes vand ships, feto.

Another object is to prow'dexa :sealing device of the -class described vabove which is leconomical ,to manufacture'and dependable under extreme conditions changes, and Amechanical stress.

of `uid pressure, temperature Another object is V,toV provide Ia sealing :device of .the vclass ydescribed above, Vhaving :a sufficient ymargin of efficiency to insure vagainst leakage evenin the case of minor irregularitiesin-:the

installation of a fastener, such-ias :fon-example,

:a al'rspot on the shank ,of the fastener, fearelessness on Vthe part vof the operatorpin drilling,

countersinkn etc. v

Another object is to provide a sealing device of ,the class described abovegwhich will 1,-not 1detract yfrom shear values obtained with conven- V:tional fasteners y VStill another object is to provide 1a sealing-device for countersunk insert type fasteners.

These andother objects -willappear as -thenvention is hereinafter .described :and `.setrforth With theadvent of high speed faircraft, it has jbecomeiessential -to utilize coimtersunkzfasteners in the outside skin to eliminate air friction and vturbulence vcaused by the protruding lheads of yothertvpe fasteners. l,and high speed lWater craft .similarly 4require the 'useof countersunk fasteners in their construction. With the development ofhigh -speed .airvcraft'has come Athe 'heightening of service v'ceiling, requiring the pressurization -of cabins. Yreduce-weight-and increase fuel carrying capaci- Y Seaplane hulls and vfloats ties, integral yWing tanks are 'being'utilized `In such applications Where sealing is zrequired, it

A-is essential that some sealing Vmeans be used in conjunction with the fcountersunk fasteners, or leaks wll occur 'during service. Count'ersunk, or other standard insert -fasteners Vof the type 'currently used, are incapable ofmaintaining-aneffec- 'tive seal. As a result, itis impossible to properly I maintain cabin pressurization; the hulls land floats* of seaplanes Vleak,requiring the `use of .1

-lbilge pumps; :and leaking gasoline tanks leans-e fires, resulting iin' loss i of ,life :as v.well fas; of :planes `and equipment. The-trend in modern fair-.craft design, toward the kattainmeni-of still .greater speeds and altitude,-willimposei-greater requirements for :the effective sealing offasteners.

A countersunk rivet or other lsuch fastener must fit `perfectly into the aperture into vwhich .it is inserted, in Vorder to obtain initial iseal.

However, during operation or Whilein service,

lvibration .imposes reverse stresses and weaving creates shear loads which generally loosen jthe fasteners, causing leaks to occur.

Many fattempts have been made 'to install countersunk fasteners in such a wayfas t0 `maintain effective 'seal under operative conditions,

y,but prior `to'this invention, .none has beenjsuc.- cessful. The application of various compounds :around the .heads of thefasteners, prior -to .in-

stallation, has proved unsuccessful because-,metal izo-metal :contact between :the fastener and the 4materials v'to ybe vsecured was ,not possible 'and therefore, 'either the fastener could :not-be tightened, or because lof cold ow :of :the compound (if iresilient) 'the vfastener loosensyafter installa tion. If vthe `compound were itoxharden, itu/911141 -either crackxand ,loose its seal, or compresszfthe same as solid metal undervibration or fshear load, Whereuponfthe fasteners would loosen-and 'the seal Would-,again belost.

kThe .application of sealing :compounds around the base of thefastener is :not satisfactory because of seepage between the layers of Y,metal fastened to the ,shank and ,around the head of V'the fastener. The vdetectionnof ,leaks under such ,f conditions isgdifiicultif vnot impossible. l

A lrecent vdevelopment has .been ,the manuliactureof a special, countersunk :rivetwithfannular ridges 'fashioned on the underside of Vthe head. When this rivet is driven, the ridges imbed themselves `lintothe layer of material :to .be

'fastenedfand Va fair initial seal isaccompli'shed.

However, vthese-ridges tend rto prevent ythe ,head ofthe rivet from properly seating itself intofthe aperture intended, thereby preventing contact of the entire head surface with the faying 'surface of the aperture. While `the device yfacilitates `initial seal, 'the "life of the seal vduring service conditions is `less than that -of a carefully installed conventional countersunk-fastener, be- *cause of inadequate bearing surface. I

The sealing device described 'in this specification-'is` the result of Yfurther lresearch rand ex- 4:perimentation following develop-ment of sealing devices, which were the :subject-matter Offmy Figure 7 is a sectional view of theline designated i.

unexpired earlier U. S. Patent No. 2,396,005. The invention has been subjected to exhaustive vibration and weaving tests in the laboratories of Rohr Aircraft Corporation, and has been found to maintain effective seal without exception. Shear strengths equal to or greater than those obtained with conventional fasteners, are possible. The device is simple and economical in its manufacture and installation.

Essentially, my invention consists of a specially formed disc shaped retainer which compresses a resilient ring of rubber-like material. To utilize my invention in the joining of sheet metal or other parts, the operator will drill a hole through the parts to be fastened, countersink the outer surface of one part to receive the head of the fastener (in the case of countersunk type fasteners), and counterbore the other part (or extreme opposite part, in the case of multiple laminations) to receive my sealing device. The fastener is then inserted in the conventional manner and the sealing device installed around the shank of the fastener and into the counterbored hole. The fastener is then tightened in a conventional manner.

During the tightening operation the rubberlike ring is compressed within the recess formed between the specially designed retainer, the shank of the fastener and the bottom surface of the counterbored hole into which the sealing de- .vice has been placed. The cross sectional area of the rubber-like ring is slightly larger than that of the said recess, and is designed so that after f the fastener has been tightened, the rubber-like material will not only l1 the recess, but will be compressed just suflciently to effect a positive seal, in a manner somewhat similar to that of a gland packing. The metal to metal contact of the fastener, the sealing device, and the parts joined, will prevent the undue compression of the rubber-like substance, i. e., will prevent its being compressed beyond a point producing permanent deformation. Where it is desired vto seal against a specific substance, such as fuel, a rubber-like material offering resistance to that substance is used in the ring. For exampleI an aromatic fuel resistant synthetic rubber, or other suitable material, will be used against gasoline.

Attention is invited to the accompanying drawing, illustrating preferred forms of my invention,

in which similar numerals of designation Yrefer to similar parts throughout the several views, and in which:

Figure l is a sectional view of two metal parts which have been fastened together by means of a countersunk rivet, showing the application of my sealing device in securing and hermetically sealing the shank of the rivet, and in which the rubber-like ring is shown compressed.

Figure 2 is a sectional view, the same as Figure `l, before the rivet has been tightened.

Figure 3 is a sectional view of the sealing device, showing a form of retainer Without the annular shear wall shown in Figures l, 2, 4, 6

and 7.

Figure 4 illustrates an arrangement where the depth of the counterbored hole exceeds the thickness of vmetal part 2 and extends into several intermediate laminations.

Figure 5 illustrates an arrangement where the depth of the counterbored hole is less than the thickness of the metal part 2.

Figure 6 is a plan view of the retainer. 4, and Figure 6, along Figure 8 is a plan view of the retainer I0, and Figure 9 is a sectional view of Figure 8, along the line designated lX-IX.

Figure l0 is a plan view of the rubber-like ring 5, and Figure 1l, is a sectional view of Figure 10 along the line designated XI-XI.

Referring to the drawing, the metal part l and the metal' part 2, which are to be'fastened together, are drilled, and the metal part I is countersunk in a conventional manner, to accommodate the head of the fastener 3. Prior to the insertion of the fastener 3, the metal part 2 is counterbored to a depth matching that of shear wall 6. It is to be noted, however, that in certain cases (as illustrated in Figure 4) the depth of the counterbored hole will exceed the thickness of metal part 2. The diameter of the counterbore is just sufficient to accommodate the outside diameter of said shear wall 6, of the retainer 4, as shown in Figures 1, 2 and 4. To fasten the parts, the fastener 3 is inserted in a conventional manner and the sealing device, consisting of the specially designed retainer 4 and the rubber-like ring 5, is installed around the shank of the fastener 3 and into the counterbored lhole in part 2, as shown in Figure 2. The fastener is then tightened in a conventional manner. With the tightening of the fastener 3, the retainer 4 is seated into the counterbored hole (as shown in Figures l and 4), causing the rubber-like ring 5 (located therewithin) to be compressed, said ring .5 having a slightly larger cross-sectional area (before compression) than that of the recess area formed between the retainer 4, the shank of the fastener 3 and said bottom surface of counterbored hole. As shown in Figures l and 4, the edge surface 'l of the shear wall 6, meets the bottom surface of the counterbored hole, while the bearing shoulder 8 of retainer 4 bears 'upon the outer surface of part 2. Metal to metal contact is thereupon established, prohibiting'overcompression of said ring 5 during completionvof the tightening operation.

Referring to Figures? and 9, hole diameter B will vary in accordance with the shank diameter of the fastener used, providing in all cases, for a slip fit.

Referring to Figures 3, 5, 8 and 9, showing a modified vform of the retainer portion of my device, the retainer I0 has a shear-curb 9, the function of whichA is similar to that of the shear wall 6 of retainer 4 shown in Figures 1, 2, 4, 6, and 7. However, it may be seen that the retainer I0 does not contact the bottom surface of the counterbored hole, and the rubber-like ring 5 is compressed directly against the Wall surface of said counterbored hole.

The preparatory operations, prior to the installation of retainer I0 are the same as described for retainer 4; the diameter of the counterbored hole being just suilicient to receive the diameter of shear-curb 9, and the depth of said counterbored hole being set to a predetermined standard.

Forms other than those shown and described hereinbefore, may be given to my invention, without deviation from the origina1 spirit or basic principle thereof; the scope of the invention being indicated by the appended claims, and all changes which come within the range of equivalency of the claims are intended to be embraced therein.

What Il claim as my invention and desire vto protect by Letters Patent is:

a crlmdrical .Shank anda lowerneaq in Contact with the lower sheet; the lower sheet having an opening adapted to pass the rivet shank and the upper sheet having a cylindrical opening extending entirely therethrough and through which the rivet shank passes; a disc shaped rigid re-l tainer Whose diameter is substantially greater than the diameter of said cylindrical opening; said retainer having a depending cylindrical projection having a free sliding t with the marginal wall of said cylindrical opening; a torus shaped ring of highly resilient material disposed within said cylindrical opening around the rivet shank, the length of the rivet shank being suflicient that upon its being upset to form a rivet head, the formed head presses against the top of said retainer to draw the sheets together and cause the base of said cylindrical projection to press against said ring by an amount just sufcient to force the ring into sealing contact with the rivet shank, the marginal Wall of the cylindrical opening and the upper face of the lower sheet, but insuiiicient to produce permanent deformation of the ring.

2. A laminated structure as claimed in claim 1; in which the opening in the lower sheet is tapered and the lower rivet head is correspondingly tapered to seat against the marginal wall of the tapered opening to provide a head flush with the exposed surface of the lower sheet.

BERNARD GROSS.

REFERENCES CITED The following references are of record in the lile of this patent: 

